The present invention relates to monolithically integrated linear image scanning circuits, and in particular to such a circuit with components for matching the varying spectral sensitivities of differently filtered sensor elements.
A monolithically integrated circuit for linear image scanning having a linear image sensor with two parallel rows of opto-electronic sensor elements is known from "IEEE Transactions On Electron Devices," Vol. ED-25, No. 2, February, 1978 at pages 125 through 131. As disclosed therein, the sensor elements in one of the rows comprise a first group which are disposed behind a color filter of a first type and the sensor elements in the other row comprise a second group which are disposed behind color filters of a second type. An array having a linear image sensor for scanning the images of a continuously moving 8 mm film, which supplies a television signal containing the information, is disclosed in BBC Report RD 1973/32 (PH-113) "Solid State Sensors: The Use of a Single Dimension 512 Element Array for Film Scanning," pages 1 through 17, published in November, 1973 by the British Broadcasting Corporation.
A problem in equipping such linear image sensors with photodiodes for use with varying colors of incident radiation is that the spectral-light sensitivity of the groups of photodiodes with the color filters results in unbalanced output signals for the different groups, that is, the sensor groups have output signals which are unmatched. The first document identified above discloses the concept of controlling the integration times of the sensor elements, however, such integration control is not undertaken for the purpose of matching or balancing the output signals to compensate for varying exposure intensities in the manner of an electronic diaphragm or iris. Such control is undertaken by a gate which covers a semiconductor zone between a series of photodiodes, which serve as the sensor elements, and which also covers storage capacitors associated with the sensor elements.
A circuit for color image scanning utilizing two rows of sensor elements with different color filters is disclosed and claimed in the co-pending application Ser. No. 75,000 (Herbst) filed July 12, 1979 based on the German application P 28 38 098.5.
Related Application
This application is related to an application of the same inventors entitled "Readout Circuit for a Monolithically Integrated Circuit for Linear Image Scanning" filed simultaneously with the present application and identified with Ser. No. 171718 filed July 24, 1980.